Method of manufacturing an aluminum alloy wheel rim

ABSTRACT

A method of manufacturing a wheel rim for a motor vehicle comprises the steps of a strip of aluminum alloy sheet material having a predetermined cross-section suitable for forming into a wheel rim by extrusion molding, pressing the strip step-by-step lengthwise by an upper mold and a lower mold having complimentary profiles for causing the strip to have predetermined profiles as a hoop with a formed gap between the both ends, welding the gap to form an unfinished wheel rim, and annealing, shaping, heat treating, and polishing the unfinished wheel rim to form a finished wheel rim.

FIELD OF THE INVENTION

[0001] The present invention relates to the field of wheel rimmanufacturing and more particularly to an improved method ofmanufacturing an aluminum alloy wheel rim.

BACKGROUND OF THE INVENTION

[0002] Methods for making wheel rims are well known. For example, U.S.Pat. No. 4,589,177 to Secolo et al. and U.S. Pat. No. 4,185,370 to Evensboth disclosed such methods. The method of Evans's Patent is illustratedin FIGS. 1 to 3. In FIG. 1, a strip 1 of aluminum sheet material used toform a wheel rim is shown. In FIG. 2, such strip 1 is formed into a hoop3 and the opposing ends flash butt welded forming weld line 2. The thusformed hoop is subsequently passed through multiple forming operations(e.g., press and roll forming operations) resulting in a finished wheelrim 4 having desired sectional profiles shown in FIG. 3.

[0003] But this is unsatisfactory for the purpose for which theinvention is concerned for the following reasons: Firstly, a variety ofexpensive rollers are employed in the roll forming operations in orderto manufacture a wheel rim having desired sectional profiles. Further,such manufacturing processes are complex, time consuming, laborintensive, and excessive energy consumption. This results in an increaseof manufacturing cost. Secondly, as stated above a series of formingoperations (e.g., press and roll forming operations) are performed onthe hoop to form a wheel rim having desired sectional profiles. But theformed wheel rim may be deformed or too thin due to non-uniform pressingin these manufacturing processes. As a result, the formed wheel rim isunbalanced in weight or unacceptable low in hardness, thus adverselyshortening the useful life of wheel rim. Thus improvement exists.

SUMMARY OF THE INVENTION

[0004] It is therefore an object of the present invention to provide amethod of manufacturing a wheel rim for a motor vehicle comprising thesteps of (a) forming a strip of aluminum alloy sheet material having apredetermined cross-section suitable for forming into a wheel rim byextrusion molding; (b) pressing the strip step-by-step lengthwise by anupper mold and a lower mold having complimentary profiles for causingthe strip to have predetermined profiles as a hoop with a formed gapbetween the both ends; (c) welding the gap to form an unfinished wheelrim; and (d) annealing, shaping, heat treating, and polishing theunfinished wheel rim to form a finished wheel rim.

[0005] The above and other objects, features and advantages of thepresent invention will become apparent from the following detaileddescription taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a perspective view showing a strip of sheet materialused to form a wheel rim by a conventional manufacturing method;

[0007]FIG. 2 is a perspective view showing the strip of FIG. 1 formedinto a hoop;

[0008]FIG. 3 is a perspective view showing the wheel rim of FIG. 1 inits final configuration;

[0009]FIG. 4 is a perspective view showing an unfinished wheel rim ofaluminum according to a first preferred embodiment of the method of theinvention;

[0010]FIG. 5 is a perspective view showing molds and rollers used toform the wheel rim according to the method of the invention;

[0011]FIG. 6 is a perspective view showing an unfinished wheel rim ofaluminum according to a second preferred embodiment of the method of theinvention;

[0012]FIG. 7 is a fragmentary enlarged view of FIG. 6;

[0013]FIG. 8 is a side view of FIG. 6;

[0014]FIG. 9 is a perspective view showing the wheel rim of FIG. 6formed into a hoop;

[0015]FIG. 10 is a sectional view taken along line X-X of FIG. 9 showinga soldering of the hoop for forming a wheel rim;

[0016]FIG. 11 is a sectional view showing the deformed hoop of FIG. 9after undergoing the step of molding; and

[0017]FIG. 12 is a sectional view showing the assembly of wheel rim ofthe invention with a disk.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Referring to FIGS. 4 to 6, there is shown a method ofmanufacturing an aluminum alloy wheel rim in accordance with theinvention comprising the steps of forming a strip 10 of aluminum alloysheet material having a predetermined cross-section suitable for forminginto a wheel rim by extrusion molding, pressing the strip 10 by an uppermold 20 and a lower mold 30 respectively, and bending both ends of strip10 to forming a bent end having a predetermined curvature θ.

[0019]FIGS. 4 and 5 show a first preferred embodiment of the invention.Upper mold 20 and lower mold 30 are activated by a lever and a seat of ahydraulic press (not shown) respectively. The pressing sides 21 and 32of molds 20 and 30 are of the cross-sections met with the predeterminedcross-section of the stripe 10 allowing the strip 10 being placedbetween molds 20 and 30. Both ends of strip 10 are bent to form apredetermined curvature θ. Once the hydraulic press is activated molds20 and 30 will press on strip 10 from opposite directions, thus forminga predetermined curvature e thereon. The degree of curvature θ isdepending on manufacturing process. Preferably, curvature θ is in therange between 15 to 60 degrees. Further, the radius of curvature θ issubstantially the same as that of formed wheel rim. In the embodiment, aroller 40 is provided in either side of upper mold 20. The wheel mounts41 of roller 40 are coupled to lever of the hydraulic press. Rollers 40are activated in synchronous with the activation of upper mold 20.Hence, the unchanged section of strip 10 adjacent to the deformedsection thereof will be deformed continuously along the curvature θ.This can prevent an undesired discontinuous deformation of strip 10between the formed section of strip 10 and the adjacent unchangedsection thereof from occurring.

[0020] As shown in FIG. 7, a lengthwise non-uniform deformation isoccurred in both ends of strip 10 each having a predetermined curvatureθ due to molecular compression of the metal strip 10. It is found thatthe deformation ΔLc in the center of the lengthwise direction of strip10 is larger than ΔLs in either side thereof. For ensuring strip 10 tobe formed as a hoop and a gap formed between two ends of the hoop afterperforming subsequent forming processes, a non-uniform deformation ΔL oneither end of strip 10 will be cut out by a bench saw as shown in FIG.8. Hence, only a desired length L of strip 10 will be preserved.Moreover, a milling machine is used to form a guide angle on either endof strip 10. As such, both ends of strip 10 may be proximate after strip10 is formed as a hoop. As an end, a V-shaped gap is formed between bothends of strip 10 (FIG. 10). Then strip 10 is again placed between molds20 and 30. The unchanged section of strip 10 is pressed step-by-step bymolds 20 and 30 lengthwise. Further, bend the strip 10 to form a hoop 50(FIG. 9). A V-shaped gap 51 is formed between both ends of hoop 50. Apoint soldering 60 is performed on the gap 51 for partially connectingthe both ends of hoop 50 together. Then a welding is performed onV-shaped gap 51 to melt the aluminum alloy solder 61 so as to unite theboth ends of strip 10 together (FIG. 10). An unfinished wheel rim 50 isthus formed. The invention then anneal the unfinished wheel rim 50 toeliminate stress concentration in the gap 51 portion by rearrange themolecular structure of the unfinished wheel rim 50. After annealed, suchunfinished wheel rim 50 is placed between an upper mold 81 and a lowermold 82 of another hydraulic press (not shown) as shown in FIG. 11.Upper mold 81 and lower mold 82 are activated by a lever and a seat ofthe another hydraulic press respectively. A wheel rim to be formed hasthe same profiles as the junction of molds 81 and 82 since molds 81 and82 have complimentary profiles. Also, any irregularity formed on theunfinished wheel rim 50 will be eliminated after molds 81 and 82pressing on the inner face of unfinished wheel rim 50. Thissubstantially forms an unfinished wheel rim 50 having a desired size. Inaddition, a series of heat treatment processes are performed on theunfinished wheel rim 50 so as to cure the metal material and increasethe strength. Moreover, a polishing is performed on uneven portion ofthe unfinished wheel rim 50 to form a finished wheel rim having a smoothsurface.

[0021] In another preferred embodiment of the method of the invention(FIG. 4), a strip 10 of aluminum alloy sheet material having apredetermined cross-section suitable for forming into a wheel rim byextrusion molding further comprises a lengthwise rib 11 thereon. In thesecond preferred embodiment of the method of the invention (FIG. 6),strip 10 is then placed between molds 20 and 30 facing a pressing side21 and a pressing side 32 thereof respectively. Upper mold 20 and lowermold 30 are activated by a hydraulic press. A well 31 is provided onpressing side 32 sized to receive the rib 11. Then a series of formingoperations (e.g., press and roll forming operations) are performed onstrip 10 to form a hoop. Thereafter, welding, annealing, shaping, heattreatment, and polishing operations are performed to form a finishedwheel rim 50 having a perimetric rib 11 along inner side. Also, aplurality of equally spaced holes 13 are formed along rib 11 (FIG. 12).A plurality of fasteners 90 are driven to fix a disk 70 onto the rib 11of wheel rim 50 through the holes 13. The wheel rim 50 may then beinstalled to axle of a motor vehicle to secure them together via thedisk 70. In brief, the advantages of the invention are the following:the equipment required is simple and inexpensive. The quality of formedaluminum alloy wheel rim is high. No welding operation is required forfastening wheel rim 50 and disk 70. The provision of rib 11 greatlyenhances the strength of finished wheel rim 50.

[0022] While the invention has been described by means of specificembodiments, numerous modifications and variations could be made theretoby those skilled in the art without departing from the scope and spiritof the invention set forth in the claims.

What is claimed is:
 1. A method of manufacturing a wheel rim for a motorvehicle comprising the steps of: forming a strip of aluminum alloy sheetmaterial having a predetermined cross-section suitable for forming intoa wheel rim by extrusion molding; pressing said strip step-by-steplengthwise by an upper mold and a lower mold having complimentaryprofiles for causing said strip to have predetermined profiles as a hoopwith a formed gap between said both ends; and welding said gap to forman unfinished wheel rim.
 2. The method of claim 1, wherein said strip ofaluminum alloy sheet material having a predetermined cross-sectionsuitable for forming into a wheel rim by extrusion molding furthercomprises a lengthwise rib 11 thereon.
 3. The method of claim 2, whereinsaid upper and lower molds are coupled to and activated by a lever and aseat of a hydraulic press respectively, pressing sides of said molds areof the cross-sections met with the predetermined cross-section of thestripe allowing the strip being placed between said molds and sandwichedby said molds having complimentary profiles, and being bent to form saidpredetermined curvature when said hydraulic press is activated and saidmolds press on said strip from opposite directions.
 4. The method ofclaim 3, wherein a degree of said curvature is in the range between 15to 60 degrees.
 5. The method of claim 3, wherein a radius of saidcurvature is substantially the same as that of said wheel rim to beformed.
 6. The method of claim 3, wherein on both sides of said uppermold further comprises a pair of rollers, each roller having a wheelmount coupled to said lever of said hydraulic press so that said rollersare capable of activating in synchronous with the activation of saidupper mold and an unchanged section of said strip adjacent to a deformedsection thereof is deformed continuously along said curvature.
 7. Themethod of claim 6, wherein after forming said stripe, further comprisesthe step of pressing on both ends of said strip to form said curvedsections by said upper and lower molds.
 8. The method of claim 7,wherein after forming said curved sections on both ends of said strip,further comprises the step of cutting out a non-uniform deformation oneither end of said strip by a saw.
 9. The method of claim 8, whereinafter cutting out said non-uniform deformation on either end of saidstrip, further comprises the step of forming a guide angle on either endof said strip by a milling machine so that both ends of said strip areproximate after said strip is formed as said hoop and a V-shaped gap isformed between both ends of said strip.
 10. The method of claim 9,wherein after both ends of said strip are proximate and said V-shapedgap is formed, further comprises the step of performing a pointsoldering on said gap for partially connecting both ends of said hooptogether.
 11. The method of claim 10, wherein after both ends of saidhoop are partially connected together, further comprises the step ofperforming a welding on said V-shaped gap to melt an aluminum alloysolder placed in said V-shaped gap so as to unite both ends of saidstrip together for forming said unfinished wheel rim.